1. Field of the Invention
This invention is concerned with a method and apparatus for non-surgical, reversible sterilization of females.
2. Description of the Prior Art
One of the more pressing problems which is encountered in the World today is that of over population. The problem of over population which has been a substantial problem for a considerable period of time in certain highly populated areas, such as Asia and the Indian Sub-Continent is now becoming a problem in less populated areas of the World such as Europe and the Americas. Over population results in such long range problems as pollution, famine and even war.
Birth control has been relied on as the principal means to control over population. In the field of birth control the prevention of conception is considerably more acceptable for controlling population growth than abortion. However, the methods heretofore suggested for contraception have had certain inherent problems which limited the applicability and effectiveness.
The ideal contraception method should be 100 percent effective in preventing conception; should not rely on willpower; should not interfere with the satisfaction of sexual relationships, and should be low in cost taking into consideration the effective life of the contraceptive method. In addition the contraceptive method must not have any harmful psychological side effects. An extremely important feature of an ideal contraceptive method especially for family planning is that it be reversible so that it will be possible to have additional children if desired.
The most common methods of contraception which are currently employed on a mass scale each have certain inherent deficiencies which limit their usefulness. The use of such techniques and devices such as rhythm, withdrawal, condoms and diaphragms and vaginal foams all have been found to be highly unreliable. The more recently promoted methods such as intrauterine devices and use of contraceptive pills likewise have certain defects which limit their effectiveness. The intrauterine devices cannot be utilized by all females and there is some indication that they cause irritation and discomfort and are often rejected by females. The contraceptive pill cannot be utilized by many females due to incompatability with their normal hormone balance. Furthermore, the use of the pill has been found to increase the risks of certain .[.carcigenic.]. .Iadd.carcinogenic .Iaddend.conditions.
There are currently two methods in wide use which are generally considered to be effective contraceptive methods. These are oviduct ligation for females and vasectomy for males. In both these methods the ducts from the reproductive organs are severed and accordingly the contraceptive technique if properly performed and there is no natural regeneration are 100% effective. However, both methods have the defect that it is difficult, if not impossible, to reverse the procedure so as to restore the normal reproductive capacity.
It has been well established by gynecologists that a primary cause of infertility in females is blockage of the oviducts from the ovary to the uterus. The ovum when discharged from the ovaries is absorbed by the body and is prevented from coming in contact with the sperm and accordingly conception does .Iadd.not .Iaddend.occur. Females having this natural condition normally do not even realize it exists and do not suffer any adverse side effect besides being infertile. Having been made aware of this natural condition those skilled in the art have suggested artificial blocking of the oviduct to impart sterility.
It was reported by Corfman et al. in Obstetrices and Gynecology Vol. 27 No. 6 pages 880-883 (June 1966) that various substances could be injected transcervically into the oviducts.
Hefnawi et al. Amr. J. Obst and Gynec, Vol. 99, No. 3 pages 421-427 (Oct. 1, 1967) reported attempts to block the oviducts by the injecting of medical grade elastomeric materials in the uncured state into the oviducts and allowing the material to solidify in the oviducts. The elastomeric material was thinned prior to injection so as to have a relatively fluid mixture for injection. The reported results obtained with rabbits was quite unsatisfactory. The incidence of pregnancy after insertion of the oviduct blocks was quite high. Effective sterilization was only achieved if the plug was placed in the medial portion of the oviduct. To remove the plug it was necessary to conduct laparotomy. A further problem which was reported was the tendency for the plug to migrate from the oviduct into either the uterine cavity or even more dangerously into the peritoneal cavity.
Rakshit reported in the Calcutta Med J 65, No. 3 (Mar., 1968) attempts to use various materials to block the oviducts to prevent conception. It was suggested to use a plastic material of a nature which solidifies after being mixed with a catalyst to form the oviduct blocks. Rakshit specifically taught however that because of high viscosity the silicone rubbers could not be injected transvaginally and laparotomies were conducted to inject the material directly into the uterus. The material was then allowed to flow into the oviducts. It was suggested in this article by Rakshit that it may be possible to introduce a plastic material transcervically into the uterus and then to allow it to flow in the oviducts. Using this method however the resulting oviduct blocks would have to be removed surgically to reestablish fertility.
Rakshit further reported in Human Sterilization edited by Ralph Rechart (1971) pages 213-221 the technique of attempting to form oviduct blocks by inserting a cannula directly into the uterus through the cervix and filling the uterus with a curable liquid silicone plastic. The injected silicone plastic was allowed to flow into the oviducts and cure in place to form the desired oviduct blocks. The excess material was then removed from the uterus. The reported results were not promising. On tests reported on 14 women there were nine satisfactory blockages, three doubtful cases and two negative cases. Further, in order to remove the oviduct blocks it was necessary to conduct a laparotomy.